The invention relates to an apparatus particularly a working machine for compressing and conveying fluids, having a rotor with a thin-walled rotary sleeve which is arranged eccentrically to the axis of the rotor and contacts the circumferential surface of the rotor through an angular range, and with at least one separator slide between work spaces or chambers, whose volume is variable upon rotation of the rotary sleeve.
U.S. Pat. No. 4,580,957 discloses an apparatus of this type, whose rotary sleeve or annular piston has a larger diameter than the piston, which is constructed as a fixed housing. The rotary sleeve is mounted in a circular drive ring, the inner space of which is displaced eccentrically of the piston housing. A spring loaded separator slide produces working chambers which vary in volume when rotation occurs, whereby the medium to be conveyed is aspirated and expelled once per revolution. The maximum possible intake volume per revolution is determined by the relationship of the diameters of the rotary sleeve and the piston. Because of the tightly crowded spatial relationships in the stationary piston housing, under practical conditions only diameter differences of from 10 to 12% can be meaningfully realized. Further, the maximum speed of rotation is limited by the follower spring arranged in the piston housing, which spring has to have a high spring tension if the follower must be extended at high frequencies. The maximum speed of rotation of this known machine is approximately 4000 revolutions per minute. A further limitation of the maximum speed of rotation is determined by the limiting speed of rotation of the roller bearings, which surround the rotary sleeve radially outwardly. Because of the additional deformation in the rolling contact region, the limiting speed of rotation of the standard roller bearing must be reduced. Further, the machine requires careful counterbalancing, particularly at higher speeds of rotation. On the other hand, with the previously known machine, pressures up to 10 bar or vacuums up to 10 millibar can be produced in a single stage, and this can be achieved with the complete absence of oil from the working chamber. The heat of compression can be conducted away in a simple manner, and the friction losses are small, so that the specific power requirement is 20 to 30% lower than in other types of construction. The previously known machine, particularly when constructed as a rotary sleeve compressor in accordance with FIG. 22 of the aforementioned U.S. patent, offers significant advantages compared to comparable machines with other types of construction because of a thermal behavior which is favorable due to the absence of loss spaces, because of the possibility of internal and external cooling, and because of low frictional losses and a consequent low power requirement.
Thus, U.S. Pat. No. 4,514,156 discloses a compressor with a rotary sleeve which has a relatively large wall thickness and is mounted in a stationary housing by an air bearing. Within the rotary sleeve a rotor is eccentrically arranged, which has a smaller diameter than the rotary sleeve and contains four radially movable separator slides or vanes. The substantially rigid rotary sleeve lies with its inner surface in contact with the outer surface of the rotor practically only along a line. A compressor of this type requires extremely precise fabrication, especially since the radial gap width of the air bearing should be less than 0.1 mm in size.
Further, French Pat. No. 1,286,068 discloses a compressor with a practically rigid, thick-walled rotary sleeve, which is mounted in a housing by roller bearings at each of its axial ends. The rotor arranged radially inside the rotary sleeve contains two diametrically opposed separator slides, which are supported with respect to each other by a spring. The rotor again lies in contact with the inner surface of the rotary sleeve practically only along a line of contact, so that difficulties result, primarily with regard to sealing and to wear.
French Pat. No. 1,548,031 also relates to a compressor with a thick-walled rotary sleeve and a rotor arranged radially inside the sleeve. Because of the aforementioned difficulties, a layer of carbon or polytetrafluoroethylene is arranged on the inner surface of the rotary sleeve.